First, referring to FIG. 1, a control technique for changing a transfer speed of a print object for a conventional inkjet recording device will be described. In an inkjet recording device, for printing the print object (also referred to as “workpiece”), ink droplets jetted from one nozzle are used. In the case where the transfer speed of the print object is relatively slow, one of every plurality of ink droplets jetted from the one nozzle is treated as a charging target and thus a charging voltage is applied thereto. The upper part of FIG. 1 illustrates an example where one of every two generated ink droplets is treated as a charging target. This case is defined as a droplet usage rate of 1/2. In order to reduce the character width of a printed result at the same transfer speed, increase in droplet usage rate as with the middle part of FIG. 1 can respond the requirements. In this example, the droplet usage rate is changed to 1/1.
As shown in the lower part of FIG. 1, increase in scan interval can also control the print character width. In this case, the generation period of the ink droplet jetted from the nozzle is set constant so as to form an optimal ink droplet shape according to an ink pressure, an ink viscosity and the like; the ink droplet is charged and then deflected and flies to a prescribed position. In the case of a fixed charging voltage, the character width of the printed result tends to get wider as the transfer speed of the print object increases.
FIG. 1 shows an example of performing one line printing. On the other hand, for instance, as shown in Patent Literature 1 (U.S. Pat. No. 5,457,484), an inkjet recording device has been invented that at least two nozzles are arranged at a printing head in the case of multi-line printing, which is for at least two lines, and printing is performed according to each nozzle and each line. This scheme has a configuration including a plurality of systems of charging voltages and deflecting voltages, the number of the plurality conforms to the number of nozzles. This scheme is effective for reducing the character width of the printed result at high speed printing in the case of multi-line printing.